Dona, Lady St. Columb, decides to visit her husband's estate in remote Cornwall with her children only to discover that the disused property is being used by a notorious pirate Jean-Benoit Aubéry who has been terrorizing the coast of Cornwall. When she gets to know the pirate himself, however, she finds herself falling in love with him even to the point of disguising herself as a boy and joining the ship's crew. Her husband arrives to attempt the capture of Aubéry, forcing Dona to choose between the two men and their individual fates.